ABSTRACT This proposal requests funding for partial support for a meeting on Lysosomes and Endocytosis as part of the Gordon Research Conference (GRC) series to be held at Proctor Academy, Andover, NH from June 17-22, 2018. Funding is also requested to support the associated Gordon Research Seminars (GRS) for 40-50 graduate student and post-doctoral trainees immediately preceding the Conference. Initiated by Christian de Duve in 1967, the Lysosomes and Endocytosis GRC has a tradition of over fifty years as a key international venue for presentation of cutting edge research in the area of endocytic membrane traffic and lysosome biology in health and in disease. High quality formal oral presentations, rigorous poster presentation sessions, and vigorous collegial debate at the Lysosomes and Endocytosis GRC will highlight new cutting-edge findings, disseminate new methods and approaches, and foster the development of new hypotheses, research directions, and collaborations. The GRC will have approximately 200 participants, including at least 40 speakers and 16 discussion leaders representing critical areas in research in endocytosis and lysosome biology, and a keynote speaker with a long history of contributions to the field. The field evolves rapidly, and the program for 2018 will include recent advances that are revealing roles for the endocytic pathway in new areas such as cancer, development, cytokinesis, signaling, innate and adaptive immunity, metabolism, neurodegeneration and genetic disease. Fifteen speakers will be selected from abstracts submitted, with one entire session devoted to discussion of new research directions. In addition, two poster sessions, each spanning two evenings, will foster in depth interactions between all participants. The requested funds will be used to support travel and registration for invited speakers, discussion leaders and junior investigators. Funds are also requested to support invitees to the associated GRS, in which trainees will be provided with background material and will be encouraged to present their data to each other and to build presentation and networking skills. Due to the central importance of the endo-lysosomal system to human physiology, and the exceptional record of success of past Lysosomes and Endocytosis Gordon Research Conferences, the support of the NCI, NIDDK, NIAID, NCATS, NINDS and NICHD, as well as other institutes, represent a critical investment in the mission of the NIH.